In view of numerous factors such as higher energy prices and environmental concerns, the production of value-added gaseous products from lower-fuel-value carbonaceous feedstocks, such as biomass, coal and petroleum coke, is receiving renewed attention. The catalytic gasification of such materials to produce methane and other value-added gases is disclosed, for example, in U.S. Pat. Nos. 3,828,474, 3,998,607, 4,057,512, 4,092,125, 4,094,650, 4,204,843, 4,468,231, 4,500,323, 4,541,841, 4,551,155, 4,558,027, 4,606,105, 4,617,027, 4,609,456, 5,017,282, 5,055,181, 6,187,465, 6,790,430, 6,894,183, 6,955,695, US2003/0167961A1, US2006/0265953A1, US2007/000177A1, US2007/083072A1, US2007/0277437A1 and GB1599932.
An efficient process for the catalytic gasification of a carbonaceous material to synthetic natural gas generally requires the presence of a catalyst to encourage the formation of methane with respect to other products, such as syngas. It has generally been contemplated to provide such a catalyst from a source external to the gasification process, for example, by providing solutions or solid compositions of a catalyst which are acquired separately from the feedstocks, adding additional costs to the process. However, as certain types of feedstock can contain compounds having catalytic activity, there exists a need in the art to develop processes for the catalytic gasification of carbonaceous materials which take advantage of such intrinsic catalysts to enable lower cost per unit energy stored by increasing the overall utilization and conversion of the feedstocks in the process.